Decarbonisation pathway

The Decarbonisation Pathway in Figure 5 sets out how emissions associated with the operation, maintenance and improvement of the Trunk Road Network will be reduced between now and 2045. It reflects a structured transition from the emissions baseline to Net Zero, informed by evidence, collaboration with industry and an assessment of technology readiness.

Figure 5 – Graph showing the decarbonisation pathway, showing emissions reductions (ktCO2e) against the Business-as-Usual scenario for different groups of interventions, as described in text before
Figure 5 – Graph showing the decarbonisation pathway, showing emissions reductions (ktCO2e) against the Business-as-Usual scenario for different groups of interventions

A suite of targeted interventions has been developed in partnership with Operating Companies and industry carbon specialists. These interventions address the main sources of emissions across materials, transport, plant and fleet, depots, and operational activities, supported by enabling policy, procurement, and behavioural change measures.

Together, the interventions in the Route Map reduce annual net emissions by approximately 85% by 2045, leaving a small volume of residual emissions. This results in emissions of approximately 16.7 ktCO₂e per year in 2045, equivalent to around 4.5 tCO₂e per kilometre of trunk road. These residual emissions will be addressed through responsible offsetting, alongside efforts to maximise carbon sequestration on land owned by Transport Scotland.

Phasing and Pace of Reductions

The pathway follows a front‑loaded approach, with rapid early reductions where proven technologies and practices are already available. Emissions are expected to reduce by around 50% by 2030, reflecting the Scottish Government’s ambition for deep emissions cuts this decade.

The rate of reduction then tapers through the 2030s as the remaining sources of emissions become more difficult to address. Progress during this period increasingly depends on the development, availability and affordability of emerging technologies and lower carbon materials. This approach balances ambition with realism, ensuring the pathway is challenging but achievable.

Key Drivers of Emissions Reductions

The largest emissions reductions are expected to come from decarbonising materials, reflecting their dominant contribution to the baseline. In particular, significant reductions are delivered through changes to asphalt, steel, and road‑marking materials.

Zero emission vehicles also play an important role, both in the transport of materials from suppliers to site and in the transition of Operating Company fleets and plant. Improvements in logistics, energy efficiency, and depot operations further support emissions reductions across all activity areas.

Innovation and the Future

The Route Map recognises that not all future solutions can be fully defined today. Improvements in materials science, vehicle technology, energy systems, and construction practices are expected to deliver additional emissions reductions over time. The pathway therefore allows for continued innovation, learning and adjustment as evidence and technologies evolve.

The Route Map is intended to be reviewed annually to reflect updated data, market developments, and policy requirements, while maintaining a clear trajectory towards Net Zero by 2045.

A summary of interventions for Maintenance and Improvement and Operations is found in Appendices 1 and 2.